Undergraduate GPA sucks; Master's GPA is great.

Just to give a brief, I originally majored in economics and did pretty terrible (3.1 GPA). After a break after graduation, I decided to go back to school and get a BS and MA in accounting. Through four of the six quarters, I have gotten a 4.0, and I am fairly confident I will get a 4.0 in the last two quarters.

I also think it is reasonable that I can get a 170 on the LSAT.

Do you think law school admissions may essentially look over my undergraduate GPA with the improved credentials? I really don't want to go to law school unless I go to a top 20 school. Am I in over my head to think I still have a shot at it?

Law school admission will be based primarily on your first undergraduate GPA and LSAT. Your second B.A. and M.A. will be soft factors, and will probably give you some boost, but it won't be huge. LSAC will calculate your GPA based only on the first degree. Soft factors are mostly helpful when you're being compared to other similarly qualified candidates. Top schools simply have so many well qualified applicants with high numbers that there isn't any incentive to take a chance on a less numerically qualified applicant. Further, the schools are obsessed with the numbers they report to LSAC.

A 3.1 GPA is low for any school in the top 20, and you'd have to compensate with a very high LSAT score. Without a real live score, however, everything is pure speculation. Sometimes people do better on the actual LSAT than they did in practice sessions, sometimes they drop. Until you have a score it's tough to weigh your options.

Even if you don't get a 170 that doesn't mean you can't go to good school. Think about what you want to do after law school, and where you want to live. It's possible that a solid local school with a good reputation is a better bet than a school that is ranked at the lower end of the top 20, but is out of state. Something to consider.

Considering I have to lower my expectations a bit, I'm probably going to look into applying to University of Minnesota, Hastings, USC, UT, and NYU; I also haven't decided if I'll apply to some nearby smaller schools. I'm aware my acceptance rate probably won't be too high. haha.

I'm probably going to look into applying to University of Minnesota, Hastings, USC, UT, and NYU;

Obviously I don't know anything about your personal situation or your future plans, but based on this statement it seems like you're making your decision based on rankings alone. I would suggest that you also consider what you want to do after law school and where you want to live. All of the school you mentioned have good reputations, but they are very different in terms of post-graduation options. With the exception of NYU, each of these schools will mostly offer opportunities within it's immediate geographic region.

Apart from a few truly elite schools (Harvard, Yale, etc) the vast majority of Tier 1 schools are essentially strong regional institutions. The fact that USNWR states that a certain school is Tier 1 does not mean that it automatically has the kind of reputation that will land you a job anywhere in the country based on pedigree alone. If you're interested in living in a particular area, you're almost always better off going to law school in that area, even at a lower ranked school.

For example, if you wanted to live in the SF/Bay Area (possibly the most LGBT friendly place in the U.S.), Hastings is probably an immeasurably better choice than, say, Minnesota. The fact that USNWR ranks Minnesota higher than Hastings does not make up for the fact that Hastings students will have better access to internships, clerkships, and summer associate positions in SF. The alumni network is strong throughout CA, and that will be very helpful when it comes time to get a job. Hastings will also better prepare you for the CA bar exam. A Minnesota grad who simply shows up after graduation without local experience will have a tough time, regardless of rankings. In fact, a USF or Golden Gate grad might even have an advantage over a Minnesota grad in that scenario. OTOH, if you want to live in the Midwest, Minnesota is a great option.

Here's the takeaway: rankings do matter, but once you get outside of the "elite" category you need to look at other criteria including location, scholarships, career goals. Good Luck!